Abstract
In the past vector relationships have been one of the criteria used for delineating plant virus taxa. The proposed family, the Potyviridae, continues that practice. Aphid transmission of viruses within the genus Potyvirus is a useful characteristic in terms of identification, but is of only limited use in terms of taxonomy. This conclusion is based on a greater understanding of the molecular biology of potyviruses. The molecular basis of aphid transmission is not well understood at the present, but these data suggest that, beyond disease diagnosis, virus identification and characterization, and potential identification of genome microheterogeneity, aphid transmission should only be considered as a minor taxonomie criterion.